Types of grip

The hand is an amazing human instrument, and can be used to grip objects in several ways. These different ways, and different types of grip strength, are typically quantified based on the way the hand is being used.
The crush grip is what is most commonly thought of as "grip". It involves a handshake-type grip, where the object being gripped rests firmly against the palm and all fingers. A strong crush grip is useful in bone-crushing handshakes or for breaking objects with pressure.
In a pinch grip, the fingers are on one side of an object, and the thumb is on the other. Typically, an object lifted in a pinch grip does not touch the palm. This is generally considered a weaker grip position. The pinch grip is used when grabbing something like a weight plate or lifting a sheet of plywood by the top edge.
A support grip typically involves holding something, such as the handle of a bucket, for a long time. This type of strength is epitomized by the "Farmer's walk", where the bucket is filled with sand or water, and carried over a long distance. A great deal of muscular endurance is necessary to have a good carrying grip.

Normative Data
There has been extensive medical and ergonomic research looking at grip strength. This has led to the generation of normative data Average values exist for both men and women. Averages also exist for different types of grip in different positions.

In medicine
Grip strength is often used in medicine as a specific type of hand strength. The purpose of this testing is diverse, including to diagnose diseases, to evaluate and compare treatments, to document progression of muscle strength, and to provide feedback during the rehabilitation process as a measure indicating the level of hand function. For example, it is used to indicate changes in hand strength after hand surgery or after a rehabilitation program. By asking subjects to maintain a maximum contraction for longer periods, it can be used as a measure of fatigue. It is also able to predict a decline in function in old age. Since the above-mentioned grips involve the action of a large number of different joints and muscle groups, grip strength is not always very sensitive to measure individual muscle groups in medicine. For this purpose, dynamometers have been developed that provide more specific information on individual muscles in the hand such as the Rotterdam Intrinsic Hand Myometer (RIHM).

In sports
Hand grip is an important, though often overlooked, component of strength in sports. However, the grip strength is most often a secondary or auxiliary function of the sport. Sports in which grip strength are included within the secondary focus include the following: climbing, horse racing, judo, brazilian jiu-jitsu, weightlifting, Fencing, and arm wrestling and baseball.

As a separate discipline
From their beginnings as odd performances at fairs and circuses, grip feats have recently gained acceptance as a sport in their own right, with competitions being held with increasing regularity. Events include one-arm deadlift, nail bending, the closing of torsion spring hand grippers, v-bar (vertical bar) lifting, and standardized pinch apparatuses. Other common events may include Rolling Thunder lifts, thickbar deadlifts, and "Blob" lifting.
The major contests are:
Champion of Champions
European Grip Championships
British Grip Championships
Münsterland Grip Challenge
Global Grip Challenge
Loddekopinge Grip Challenge
Meisterhaft Pinzettenherren Pjasjma
Australian Grip Championships
German Grip Championships
Backyard Bastard Bash

Exhibitions and feats of strength
Aside from functional uses of a powerful grip, traditional strength feats such as ripping decks of cards or phonebooks in half experienced renewed popularity after Clayton Edgin posted a video tutorial at an online magazine Heavy Sports.